It frequently happens in missiles with ram jet drives for aerodynamic and design reasons that the airframe cross section is not larger or is only insignificantly larger than the maximum cross section of the engine. Thus, it is usually difficult to integrate additional functional elements within the airframe in the area of the engine. If rocket engines that are independent from the outside air are used as drives, these usually have a greatly contracted nozzle throat, i.e., a greatly reduced diameter in the area between the combustion chamber and the thrust nozzle, because of the high operating pressures. Since this area usually coincides with the tail plane area of the missile, it appears logical to integrate vane boosters, linkages, vane bearings, etc., here in the airframe. The cross section of the combustion chamber is sometimes smaller than the thrust nozzle, so that additional possibilities of installation will arise. However, the trend is increasingly toward air-breathing drives for good reasons, e.g., efficiency and range. Ram jet drives are especially suitable for smaller to medium-sized missiles because of their simple, robust and inexpensive design. However, since these operate with relatively low operating pressures, they require relatively large flow cross sections, and the nozzle throat is contracted only slightly. Thus, this type of engine unfortunately leads to extremely crowded installation conditions for the vane kinematics. The airframe contour is frequently also subject to interface requirements on the part of the firing or carrier devices, the carrier airplane itself, etc., especially in the case of the replacement of existing missiles with improved versions, so that even locally limited expansions of the cross section are frequently impossible.
Missiles have been known in which air intakes placed on the airframe contour on the outside are extended in the form of wake shafts to the tail of the missile primarily for fluidic reasons. If not used for other purposes, these wake shafts may be used for the installation of elements of the vane motor.